1.Introccnamahdys.ppt
- 1. 1 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony Introduction to Packet Voice Technologies Cisco Networking Academy Program
- 2. 2 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Traditional Telephony
- 3. 3 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Basic Components of a Telephony Network
- 4. 4 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Central Office Switches
- 5. 5 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 What Is a PBX?
- 6. 6 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Basic Call Setup
- 7. 7 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Supervisory Signaling
- 8. 8 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Address Signaling Tone telephone DTMF dialing • Rotary telephone – Pulse dialing
- 9. 9 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Informational Signaling
- 10. 10 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Digital vs. Analog Connections
- 11. 11 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Time-Division Multiplexing
- 12. 12 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Frequency-Division Multiplexing
- 13. 13 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Packetized Telephony Networks
- 14. 14 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Packet Telephony vs. Circuit-Switched Telephony • More efficient use of bandwidth and equipment • Lower transmission costs • Consolidated network expenses • Increased revenue from new services • Service innovation • Access to new communications devices • Flexible new pricing structures
- 15. 15 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Call Control
- 16. 16 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Distributed Call Control
- 17. 17 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Centralized Call Control
- 18. 18 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Packet Telephony Components
- 19. 19 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Real-Time vs. Best-Effort Traffic • Real-time traffic needs guaranteed delay and timing. • IP networks are best-effort with no guarantees of delivery, delay, or timing. • Solution is quality of service end-to-end.
- 20. 20 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Foreign Exchange Station Interface
- 21. 21 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Foreign Exchange Office Interface
- 22. 22 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 E&M Interface
- 23. 23 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 T1 Interface
- 24. 24 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 E1 Interface
- 25. 25 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 BRI
- 26. 26 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Physical Connectivity Options
- 27. 27 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Cisco IP Phone
- 28. 28 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Analog Voice Basics
- 29. 29 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Local Loops
- 30. 30 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Types of Local-Loop Signaling • Supervisory signaling • Address signaling • Informational Signaling
- 31. 31 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 On Hook
- 32. 32 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Off Hook
- 33. 33 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Ringing
- 34. 34 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Ringing (Cont.)
- 35. 35 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Pulse Dialing
- 36. 36 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Dual Tone Multifrequency
- 37. 37 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Informational Signaling with Call-Progress Indicators
- 38. 38 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Trunks
- 39. 39 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Foreign Exchange Trunks • Foreign Exchange Office Connects directly to office equipment Used to extend connections to another location • Foreign Exchange Station Connects directly to station equipment Used to provision local service
- 40. 40 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Types of Trunk Signaling • Loop start • Ground start • E&M Wink Start • E&M immediate start • E&M delay start
- 41. 41 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Loop-Start Signaling
- 42. 42 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Ground-Start Signaling
- 43. 43 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 E&M Signaling • Separate signaling leads for each direction • E-lead (inbound direction) • M-lead (outbound direction) • Allows independent signaling
- 44. 44 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 E&M Type I
- 45. 45 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 E&M Type V
- 46. 46 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 E&M Type II
- 47. 47 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 E&M Type III
- 48. 48 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 E&M Type IV
- 49. 49 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Trunk Supervisory Signaling— Wink Start
- 50. 50 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Trunk Supervisory Signaling— Immediate Start
- 51. 51 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Trunk Supervisory Signaling— Delay Start
- 52. 52 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 2-Wire to 4-Wire Conversion and Echo • Echo is due to a reflection. • Impedance mismatch at the 2-wire to 4-wire hybrid is the most common reason for echo.
- 53. 53 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Echo Is Always Present • Echo as a problem is a function of the echo delay and the loudness of the echo.
- 54. 54 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Echo Suppression
- 55. 55 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Echo Cancellation
- 56. 56 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Analog-to-Digital Voice Encoding
- 57. 57 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Digitizing Analog Signals 1. Sample the analog signal regularly. 2. Quantize the sample. 3. Encode the value into a binary expression. 4. Compress the samples to reduce bandwidth, optional step.
- 58. 58 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Basic Voice Encoding: Converting Digital to Analog 1. Decompress the samples, if compressed. 2. Decode the samples into voltage amplitudes, rebuilding the PAM signal. 3. Filter the signal to remove any noise.
- 59. 59 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Nyquist Theorem
- 60. 60 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Voice Compression Techniques • Waveform algorithms PCM ADPCM • Source algorithms LDCELP CS-ACELP
- 61. 61 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Example: Waveform Compression • PCM Waveform coding scheme • ADPCM Waveform coding scheme Adaptive: automatic companding Differential: encode changes between samples only • ITU standards: G.711 rate: 64 kbps = (2 * 4 kHz) * 8 bits/sample G.726 rate: 32 kbps = (2 * 4 kHz) * 4 bits/sample G.726 rate: 24 kbps = (2 * 4 kHz) * 3 bits/sample G.726 rate: 16 kbps = (2 * 4 kHz) * 2 bits/sample
- 62. 62 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Compression Bandwidth Requirements
- 63. 64 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Perceptual Speech Quality Measurement
- 64. 65 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Signaling Systems
- 65. 66 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 T1 Digital Signal Format
- 66. 67 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Robbed-Bit Signaling
- 67. 68 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Channel Associated Signaling—T1
- 68. 69 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 E1 Framing and Signaling
- 69. 70 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Channel Associated Signaling—E1
- 70. 71 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Common Channel Signaling
- 71. 72 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 ISDN • ISDN Part of network architecture Definition for access to the network Allows access to multiple services through a single access Used for data, voice, or video • Standards-based ITU recommendations Proprietary implementations
- 72. 73 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 ISDN Network Architecture
- 73. 74 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0 Layer 3 (Q.930/931) Messages
- 74. 75 © 2005 Cisco Systems, Inc. All rights reserved. Cisco Public IP Telephony v1.0